When making caramel sauce (this one was for a Vietnamese caramel & black pepper sauce) do not use a plastic spatula. As the sugar is bubbling away you'll notice small flecks of white plastic melting into your caramel. Then on discovering your mistake do not try and pick out the plastic (burnt finger) and then do not pour it into a metal bowl and stick a slotted wooden spoon into the rapidly hardening sugar and plastic mix.